Java 8 时间日期

啦啦啦

package lime.java1_8.time;


import java.time.*;
import java.time.format.DateTimeFormatter;
import java.time.temporal.TemporalAdjusters;
import java.util.Date;

/**
 * @Author liangmy
 * @Date 2018/7/16
 */
public class Localdatetime {
    public static void main(String[] args) {
        // 取当前日期：
        LocalDate today = LocalDate.now();
        System.out.println(today);
        // 根据年月日取日期，12月就是12：
        LocalDate crischristmas = LocalDate.of(2018, 07, 16);
        System.out.println(crischristmas);
        // 根据字符串取：
        LocalDate endOfFeb = LocalDate.parse("2018-07-16");
        System.out.println(endOfFeb);
        // 取本月第1天：
        LocalDate firstDayOfThisMonth = today.with(TemporalAdjusters.firstDayOfMonth());
        System.out.println(firstDayOfThisMonth);
        // 取本月第2天：
        LocalDate secondDayOfThisMonth = today.withDayOfMonth(2);
        System.out.println(secondDayOfThisMonth);
        // 取本月最后一天，再也不用计算是28，29，30还是31：
        LocalDate lastDayOfThisMonth = today.with(TemporalAdjusters.lastDayOfMonth());
        System.out.println(lastDayOfThisMonth);
        // 取下一天：
        LocalDate firstDayOf2018 = lastDayOfThisMonth.plusDays(1);
        System.out.println(firstDayOf2018);
        // 取2018年1月第一个周一，这个计算用Calendar要死掉很多脑细胞：
        LocalDate firstMondayOf2018 = today.withMonth(1).with(TemporalAdjusters.firstInMonth(DayOfWeek.MONDAY));
        System.out.println(firstMondayOf2018);

        //LocalTime包含毫秒：
        LocalTime now = LocalTime.now();
        System.out.println(now);
        //清除毫秒数：
        LocalTime nowWithNano0 = LocalTime.now().withNano(0);
        System.out.println(nowWithNano0);
        //构造时间:
        LocalTime zeroHM = LocalTime.of(0,0);
        System.out.println(zeroHM);
        LocalTime zeroHMS = LocalTime.of(0, 0, 0);
        System.out.println(zeroHMS);
        LocalTime zeroHMSN = LocalTime.of(0, 0, 0, 0);
        System.out.println(zeroHMSN);
        LocalTime midHMStr = LocalTime.parse("12:00");
        System.out.println(midHMStr);
        LocalTime midHMSStr = LocalTime.parse("12:00:00");
        System.out.println(midHMSStr);

        //创建一个LocatDateTime实例
        LocalDateTime localDateTimeNow = LocalDateTime.now();
        System.out.println(localDateTimeNow);
        LocalDateTime localDateTimeOf = LocalDateTime.of(2018,1, 1, 00, 00, 00, 12);
        System.out.println(localDateTimeOf);

        //Instant : 时间戳
        //默认使用 UTC 时区
        Instant insNow = Instant.now(); 
        System.out.println(insNow);

        OffsetDateTime insUTC8 = insNow.atOffset(ZoneOffset.ofHours(8));
        System.out.println(insUTC8);

        System.out.println(insNow.getNano());

        // 获取 UTC时区1970年1月1日午夜时分 之后 5 秒的 时间戳
        Instant ofEpochSecond = Instant.ofEpochSecond(5);
        System.out.println(ofEpochSecond);

        //Duration:用于计算两个“时间”间隔
        //Period:用于计算两个“日期”间隔

        LocalTime startTime = LocalTime.now();
        LocalTime endTime = startTime.plusHours(1).plusMinutes(2).plusSeconds(3).plusNanos(4);
        Duration duration = Duration.between(startTime, endTime);
        System.out.println(duration);
        System.out.println(duration.getUnits());
        System.out.println(duration.getSeconds());
        System.out.println(duration.getNano());

        LocalDate startDay = LocalDate.now();
        LocalDate endDay = startDay.plusYears(1).plusMonths(2).plusDays(3).plusWeeks(4);
        Period period = Period.between(startDay, endDay);
        System.out.println(period);
        System.out.println(period.getYears());
        System.out.println(period.getMonths());
        System.out.println(period.getDays());
        System.out.println(period.getUnits());
        System.out.println(period.getChronology());

        //TemporalAdjuster :时间校正器

        LocalDate with = today.with(TemporalAdjusters.next(DayOfWeek.MONDAY));
        System.out.println(with);

        //DateTimeFormatter
        //预定义的标准格式
        //语言环境相关的格式
        //自定义的格式
        DateTimeFormatter dateTimeFormatter = DateTimeFormatter.ofPattern("yyyy年MM月dd日 HH:mm:ss E");
        String localDateTime = LocalDateTime.now().format(dateTimeFormatter);
        System.out.println(localDateTime);

        //时区的处理
        //ZonedDate、 ZonedTime、 ZonedDateTime
        //其中每个时区都对应着 ID，地区ID都为 “{区域}/{城市}”的格式 Asia/Shanghai
        //ZoneId：该类中包含了所有的时区信息
        //getAvailableZoneIds() : 可以获取所有时区时区信息
        //of(id) : 用指定的时区信息获取 ZoneId 对象
        LocalDateTime zoneAsiaShanghai = LocalDateTime.now(ZoneId.of("Asia/Shanghai"));
        System.out.println(zoneAsiaShanghai);
        LocalDateTime zoneSystemDefault = LocalDateTime.now(ZoneId.systemDefault());
        System.out.println(zoneSystemDefault);

        //from(Instant instant)
        //toInstant()

        // Long - Instant
        Instant instant = Instant.ofEpochMilli(System.currentTimeMillis());
        System.out.println(instant);

        //Instant - Long
        Long timestamp = Instant.now().toEpochMilli();
        System.out.println(timestamp);

        // Date - LocalDateTime
        LocalDateTime date2LocalDateTime = LocalDateTime.ofInstant(new Date().toInstant(), ZoneId.systemDefault());
        System.out.println(date2LocalDateTime);

        // Date - LocalDate
        LocalDate date2LocalDate = date2LocalDateTime.toLocalDate();
        System.out.println(date2LocalDate);

        // Date - LocalTime
        LocalTime date2LocalTime = date2LocalDateTime.toLocalTime();
        System.out.println(date2LocalTime);

        // LocalDateTime - Date
        Date localDateTime2Date = Date.from(date2LocalDateTime.toInstant(ZoneOffset.ofHours(8)));
        System.out.println(localDateTime2Date);

        // LocalDate - Date
        Date localDate2Date = Date.from(date2LocalDate.atStartOfDay().toInstant(ZoneOffset.ofHours(8)));
        System.out.println(localDate2Date);

        // LocalTime - Date
        Date localTime2Date = Date.from(LocalDateTime.of(LocalDate.now(), date2LocalTime).toInstant(ZoneOffset.ofHours(8)));
        System.out.println(localTime2Date);


    }
}

啦啦啦